Advancing brain drug delivery: Focused magnetic hyperthermia and magnetic particle imaging for real-time BBB modulation

Abstract

The blood-brain barrier (BBB) is crucial for brain protection but limits therapeutic delivery for neurological disorders. This study utilizes magnetic hyperthermia (MH) to transiently and reversibly open the BBB, with magnetic particle imaging (MPI) enabling real-time, high-sensitivity monitoring. Using field-free point (FFP)-based focused heating, MH facilitated magnetic nanoparticles (MNPs) penetration into the brain and prolonged retention in the target area. Fluorescence imaging was confirmed on Evans blue staining to analyze BBB permeability immediately after MH, while MPI quantification revealed significant MNPs accumulation at target sites in focused-heated groups compared to non-heated controls. Fluorescence images further showed that BBB permeability restored after 24 hours, though MNPs retention persisted in heated regions for more than 72 hours. Fluorescence imaging confirms BBB permeability immediately after MH, while MPI provides both qualitative imaging and quantitative data on MNPs distribution and retention. These findings indicate that MPI can detect particle retention and distribution patterns that are not visible with Fluorescence imaging. © 2025 Elsevier B.V., All rights reserved.